Rationale for Guideline for "Time of referral to Nephrologists"

Time of Referral to Nephrologists

Contribution from the Canadian Society of Nephrology Clinical Practice Guidelines Committee

Source: CSN Position Statements extracted from “Care and Referral of Adult Patients with Reduced Kidney Function”, 2006 edition (available at http://csnscn.ca).

Referral to a nephrologist is recommended in the following situations:

1. acute renal failure

2. eGFR < 30 ml/min/1.73m2

3. progressive loss of kidney function

4. persistent proteinuria on dipstick, or quantified protein to creatinine ratio (PCR) >100 mg/mmol or urine albumin to creatinine ratio (ACR) of >60mg/mmol. Persistent is defined as present on 2 out of 3 urine samples; this indicates proteinuria of significant degree requiring investigation. (Note: a PCR of 100 mg/mmol corresponds to an approximate 24 hour protein excretion rate of 900-1000 mg)

5. if the practitioner is unable to achieve treatment targets for blood pressure, is unable to maintain the use of ACEi/ ARB or other renal protective or cardiovascular protective strategies, or feels otherwise sufficiently unprepared to manage the CKD patient, the CSN would recommend referral to a nephrologist or internist. Again, this would be dependent on local resources and disease severity, and will not apply to all locations.

Rationale: Given the lack of evidence in this area, the above statements are opinion based and were not graded by level of evidence. As such, they are referred to as ‘Position Statements’ and not ‘Clinical Practice Guidelines’.

With that in mind, statements ‘a’ and ‘e’ above are purely opinion based. Statements ‘b’, ‘c’, and ‘d’ are based upon the following data:

• Most patients with CKD do not develop progressive kidney disease and do not progress to ESRD^1-3; patients that do progress can be recognized by the presence of significant proteinuria⁴ or the presence of previous progression².

• Although metabolic abnormalities can begin early in CKD5, intervention by a nephrologist or a nephrology team is often not required until the eGFR is < 30 ml/min/1.73m².

• Six to twelve months is required to prepare a patient for kidney replacement therapy (dialysis or transplantation)6. Referral at an eGFR of 30 ml/min/1.73m² provides ample time for this preparation.

References:

1. Keith DS, Nichols GA, Gullion CM et al: Longitudinal follow-up and outcomes among a population with chronic kidney disease in a large managed care organization. Arch Intern Med 164:659-663, 2004.

2. Hemmelgarn BR, Zhang J, Manns B, Tonelli M, Larsen E, Ghali WA, Southern D, McLaughlin K, Mortis G, , and Culleton BF. Progression of kidney dysfunction in the community dwelling elderly. Kidney International 69:2155-61, 2006.

3. Rahman M, Pressel S, Davis BR, Nwachuku C, Wright JT Jr, Whelton PK, Barzilay J, Batuman V, Eckfeldt JH, Farber MA, Franklin S, Henriquez M, Kopyt N, Louis GT, Saklayen M, Stanford C, alworth C, Ward H, Wiegmann T; ALLHAT Collaborative Research Group. Cardiovascular outcomes in high-risk patients stratified by baseline glomerular filtration rate. Ann Intern Med 144:172-80, 2006.

4. Jafar TH, Stark PC, Schmid CH, Landa M, Maschio G, de Jong PE, de Zeeuw D, Shahinfar S, Toto R, Levey AS; for the AIPRD Study Group. Progression of chronic kidney disease: the role of blood pressure control, proteinuria, and angiotensin-converting enzyme inhibition: a patient-level meta-analysis. Ann Intern Med 139:244.52, 2003.

5. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis 39:S1-266, 2002.

6. Mendelssohn DC, Barrett BJ, Brownscombe LM et al: Elevated levels of serum creatinine: recommendations for management and referral. CMAJ 161:413-417, 1999.